1. Field of the Invention
The present invention relates generally to a system for transmitting an optical signal using multiple wavelengths, such as a wavelength division multiplexing (WDM) system. More particularly, the present invention relates to a device and method for fixing an optical wavelength in a WDM system that can fix the optical wavelength generated by a laser diode (LD).
2. Description of the Related Art
In general, optical communication technology is at a state where an optical fiber can transmit a large capacity of information at a high data rate and prevent a signal defect or cross-talk resulting from electromagnetic flux. Accordingly, it has been applied in various different applications. In addition, communication capacity has increased many fold due to development of the information field, particularly the internet, and thus there are increasing demands for large capacity optical communication. One way to increase the data rate of an optical signal is to increase the capacity of optical communication, but this technique has failed to satisfy such high demands. As such, there is high demand for transmitting optical data using a WDM system, which transmits a plurality of wavelengths through a single optical fiber.
In the WDM system, a plurality of wavelengths has its own wavelength properties and interfere with each other according to the corresponding wavelength properties. The corresponding wavelengths must be fixed by a special device in order to prevent their mutual interferences. The WDM system has a different structure from a general time-division-multiplexing (TDM) system, which does not multiplex the wavelength and consequently does not require fixing the wavelength of the LD.
As described above, the WDM system requires a filter device to filter a light having a predetermined wavelength existing within the spectrum of the light emitted by the LD. The filter device includes a filter for passing the predetermined optical wavelength through, and the filter is adhered and fixed in a certain position by way of soldering, laser welding, or epoxy bonding.
However, when the filter is aligned and fixed as mentioned above, an alignment device is required for angle alignment, and at least one high-priced integrated process is necessary for filter fixation (soldering, laser welding and epoxy bonding). Further, in the case where the alignment and fixation are individually performed, at least two processes are necessary, which increases device dependency and fabrication expenses.